The ornamental design for the wall mount with arm extension support, as shown and described.
FIG. 1 is a top front left perspective view of the wall mount with arm extension support with fully extended arm and front cover plates detached;
FIG. 2 is a top rear left perspective view of the wall mount with arm extension support shown in FIG. 1;
FIG. 3 is a front plan view of the wall mount with arm extension support shown in FIG. 1 with the front cover plates detached;
FIG. 4 is a rear plan view of the wall mount with arm extension support shown in FIG. 1;
FIG. 5 is a left plan view of the wall mount with arm extension support shown in FIG. 1 without front cover plates, the right plan view being a mirror image thereof;
FIG. 6 is a front plan view of the wall mount with arm extension support shown in FIG. 1 with folded arm;
FIG. 7 is a rear plan view of the wall mount with arm extension support shown in FIG. 6 with folded arm;
FIG. 8 is a top front left perspective view of the wall mount with arm extension support shown in FIG. 6 with folded arm; and,
FIG. 9 is a left plan view of the wall mount with arm extension support shown in FIG. 6 with folded arm.